Originally Posted by craig_will2513
yeah but iv dome a water change and it hasnt touched it
It is going to take more than one water change. For example, let's say your nitrates are at 160 ppm
which I think is the max on the test. If you do a 50% water change, those nitrates will drop to 80. Then, a subsequent 50% change would drop it to 40, another 25% change would drop it to about 30 and so on. You can't just do one 20% change and expect the nitrates to disappear as your nitrogen cycle is still ongoing and your system is creating nitrates even as you are removing them.
The idea is that you need to get ahead of the cycle by removing more ntrates than are being produced. The absorbers I gave you earlier can help you get ahead of what is being produced but they aren't going to keep Nitrates from being produced. I had a nitrate problem as well. I do water changes weekly yet my Nitrates were always hgher than I wanted. I added the absorbers after getting the nitrates down to the normal level and they help keep the "high" a little lower so my water change is more effective.
You indicated earlier, I believe, that you tested your replcement water for nitrates and the reading was 0, so the only place you have nitrates is within the tank. As several have indicated, the only way to get the nitrates down is through multiple water changes in a short period of time then do water changes more often to keep the nitrates down. If you are doing 20% weekly, try 15% twice a week.